Progress on Epidemiology of Influenza A(H1N1)

Abstract

Pandemic influenza A(H1N1) in 2009 is an acute respiratory infectious disease caused by the mutated novel influenza A(H1N1) virus. Patients usually present with influenza-like symptoms, and some may progress to severe cases. Influenza A(H1N1) was once called “human infection” with swine influenza virus, and novel H1N1 influenza in the early stage. Later, it was confirmed that the pathogen of this influenza was not the classical swine influenza virus, but a mutated novel virus. The World Health Organization (WHO) officially named this influenza as pandemic influenza A(H1N1), and the virus was known as human A(H1N1) virus. The virulence of influenza A(H1N1) is strong and can be spread across species. After the outbreak, Chinese scientists developed a safe and effective licensed influenza A(H1N1) vaccine, inoculating 105 million people nationwide, and establishing a large-scale vaccine safety surveillance system. With the further development of the epidemic, the activity and virulence of the virus gradually weakened, and influenza A (H1N1) gradually evolved into a subtype of seasonal influenza. In recent years, the overall global activity of influenza A (H1N1) is low, but it is still active in some tropical regions.